Ok, here's how I did the math. Tear me apart. And if you'd bother to re-read what I typed the first time, I said I "figured" "forumlated" and "should" a number of times. I realize the actual numbers may or may not bear out in real world testing, which I plan to do at some point in time, but I suspect proportionately they should be close.

318 fps with a 332 grains arrow at 70# (not 350, as I deducted 18 grains to make up for my 2" shorter draw length than the 30" ibo, there's a whole nother thread on why, read it if your skeptical). Now, the 542 grain arrow is 210 grains heavier than the 332 grain arrow. Dividing this by 5 (loss of 1 fps per 5 grains of added weight) gives you 42 fps ESTIMATED lost. 318-42= 276 fps. Did I screw something up?

For what it's worth, I shoot nothing other than a speed nok on my string, and my diamond hornet has the bowtech post feed sabre cam. I have no idea what bow Silentassasin is shooting, but I do know my bow seems faster than most around here, which are primarily hoyt and mathews. When I bought it, I had planned on a Mathews MQ-32, but with the identical set up and arrow, the Mathews chrono'd 50 fps SLOWER. And my bow had 60# limbs on it, a bunch of junk on the string (kisser, peep, two brass nocks, elimnator button, a set of string silencers) and the arrow wasn't IBO. It chrono'd around 275. It's much, much faster now.